Conventional manholes include a lower or bottom pad, a barrel having a relatively constant diameter adjacent the pad, a concentric or eccentric cone extending upwardly from the barrel, one or more adjusting rings to adjust the overall height of the manhole, and a casting frame on top of the adjusting rings to support a lid at an elevation substantially level with the surrounding pavement. The casting frame is preferably sealed to the uppermost adjusting ring to preclude or minimize water flow into the manhole. The cone and adjusting rings are commonly known as the manhole chimney. Most manhole structures are unique in size and shape with varying diameters and depths. Also, bricks often form a portion of the wall of a manhole.
Substandard construction methods can lead to damage or deterioration of the manhole structure. Thus, the manhole is vulnerable, allowing water and subsidence of soil to enter the manhole, which eventually leads to structural failure of the manhole.
One method of repairing manholes is the placement of a coating of a cementitious grout onto the interior surface of the manhole wall. The grout is applied in an uncured state and is permitted to cure. Methods of applying the grout include troweling the grout onto the wall of the manhole after spraying or slinging the grout onto the wall of the manhole. However, it is necessary for a person applying the grout to enter into the manhole. In addition, a final troweling step is usually required in order to obtain the desired compaction, surface, and thickness for the grout material.
Another method of repairing includes the use of cured-in-place (CIP) liners, which are coated with a resin. The liners are inserted into the manholes, and then expanded to contact the wall of the manhole. The CIP liners are then allowed to cure, which creates a new interior surface of the manhole wall. However, the wall may still contain cracks, joints, holes, or other defects that could be penetrated by ground water. The ground water could seep into the manhole, which would structurally weaken the wall of the manhole further. Additionally, if the defects are not sealed or the CIP liner is not permanently bonded to the manhole, water could seep down between the wall of the manhole and the CIP liner, and could weaken or damage the lower pad or pipes located at the bottom of the manhole.
Accordingly, there is a need in the art for an improved method and apparatus that overcomes the problems resulting from ground water being allowed to penetrate the wall of a manhole through defects and damages in the wall. There is also a need in the art for a method and apparatus for both sealing the wall of a manhole from ground water, while also structurally renewing the same wall at the same time.